Selenium is an essential antioxidant trace element that is necessary for key activities in human metabolism [Djalalinia 2019]. Meta-analyses of randomized controlled trials of selenium supplementation reveal that selenium supplementation is a cost-effective and simple-to-use intervention that can play an important role in the prevention of heart disease risk factors [Hasani 2018; Hasani 2019; Mahdavi 2019; Tabrizi 2017].
These results from meta-analyses of randomized controlled trials reaffirm the outcomes in the Bomer multinational observational cohort study. In that study, heart failure patients with serum selenium concentrations below 70 micrograms per liter were more likely to have the following characteristics [Bomer 2019]:
- more often women
- worse New York Heart Association functional class
- more severe signs and symptoms of heart failure
- poorer exercise capacity (6-minute walking test)
- poorer quality of life
Many of the same characteristics were typical of heart failure patients with serum selenium concentrations below 100 micrograms per liter. The researchers concluded that selenium deficiency in heart failure patients is associated with impaired exercise capacity, with a 50% higher mortality rate, and with impaired mitochondrial function in heart muscle cells [Bomer 2019].
Selenium Supplementation and the Effect on Oxidative Stress Bio-Markers
Researchers investigated 13 studies (12 randomized controlled trials and one crossover study) enrolling 2790 study participants. They assessed the effect of selenium supplementation on antioxidant bio-markers. The meta-analysis showed that selenium supplementation significantly increased the levels of the antioxidant enzyme glutathione peroxidase and increased total antioxidant capacity while significantly decreasing the levels of malondialdehyde, a known bio-marker for oxidative stress [Hasani 2019].
Selenium Supplementation and the Effect on Cholesterol and Triglycerides
Researchers reviewed 11 studies enrolling 1221 participants. They found that the intake of selenium supplements resulted in a statistically significant improvement in total cholesterol levels, in triglyceride levels, and in very low-density lipoprotein levels. The selenium supplementation did not significantly improve low-density lipoprotein levels, high-density lipoprotein levels, or high-density lipoprotein to total cholesterol ratios [Hasani 2018].
Selenium Supplementation and the Effect on Glycemic Indexes
Researchers carried out a meta-analysis of 12 double-blinded, placebo-controlled studies published between 2004 and 2016 (selenium intervention group: n = 757; placebo control group: n = 684) [Mahdavi 2019].
The selenium supplementation significantly decreased HOMA-B (beta-cell function). The selenium supplementation significantly increased insulin sensitivity as measure on the Quantitative Insulin Sensitivity Check Index (QUICKI) [Mahdavi Gorabi 2019]. With the selenium supplementation, there was, seemingly, less secretory demand on the beta-calls, perhaps because of improved insulin sensitivity.
Selenium supplementation was not significantly associated with any changes in the following measurements, suggesting that the selenium supplementation did not increase or decrease the risk of developing type-2 diabetes:
- fasting plasma glucose levels
- insulin levels
- HOMA-IR insulin resistance scores
- HbA1c levels (average level of blood sugar over past 2-3 months)
- adiponectin levels (protein hormone needed for blood glucose regulation)
A 2017 meta-analysis showed that selenium supplementation of patients diagnosed with metabolic syndrome was associated with a significant increase in the QUICKI insulin sensitivity score but was not associated with any changes in fasting plasma glucose and insulin resistance [Tabrizi 2017].
A 2016 randomized controlled trial showed that 200 mcg/day of selenium supplementation of patients with Type-2 diabetes and coronary heart disease resulted in significant decreases in insulin levels, insulin resistance scores, beta-cell function scores, and serum hs-CRP levels and in significant increases in QUICKI scores and in total antioxidant capacity [Farrokhian 2016].
Selenium in Combination with Coenzyme Q10 and the Effect on Heart Function
In the Kisel-10 Study, Professor Urban Alehagen tested the effect of combined selenium supplementation (200 mcg/day) and Coenzyme Q10 supplementation (2 x 100 mg/day) on non-institutionalized senior citizens for four years. The data from the study showed 50% reduced risk of death from heart disease, improved heart function, and better quality of life in the active treatment group. Professor Alehagen suggested that the reduced oxidative stress, lower inflammation levels, reduced fibrosis, and increased insulin-like growth factor-1 levels as possible mechanisms explaining the protective effects of selenium and Coenzyme Q10 on the heart muscle [Alehagen 2013; 2018].
The Take-Home Message: Selenium and Heart Health
- Selenium is an essential micronutrient in human metabolism.
- Selenium’s antioxidant and anti-inflammatory effects play an important role in the prevention of heart disease.
- Selenoprotein enzymes such as glutathione peroxidase and thioredoxin reductase protect against oxidative damage and help to regulate immune system processes.
- There seems to be a synergistic interrelationship between selenium and Coenzyme Q10 that protects the heart muscle [Alehagen 2015].
Alehagen, U., Johansson, P., Björnstedt, M., Rosén, A., Post, C., & Aaseth, J. (2016). Relatively high mortality risk in elderly Swedish subjects with low selenium status. European Journal of Clinical Nutrition, 70(1), 91-96.
Alehagen, U., & Aaseth, J. (2015). Selenium and Coenzyme Q10 interrelationship in cardiovascular diseases–A clinician’s point of view. Journal of Trace Elements in Medicine and Biology, 31: 157-162.
Alehagen, U., Aaseth, J., Alexander, J., & Johansson, P. (2018). Still reduced cardiovascular mortality 12 years after supplementation with selenium and coenzyme Q10 for four years: A validation of previous 10-year follow-up results of a prospective randomized double-blind placebo-controlled trial in elderly. Plos One, 13(4), e0193120.
Bomer N, Grote Beverborg N, Hoes MF, et al. Selenium and Outcome in Heart Failure. Eur J Heart Fail. 2019, 10.1002/ejhf.1644.
Djalalinia S, Khosravi M, Hasani M, et al. Effects of Selenium Supplementation on Cardiometabolic Risk Factors, Inflammatory, and Antioxidant Markers: A Systematic Review and Meta-analysis Protocol. Int J Prev Med. 2019;10:213.
Farrokhian A, Bahmani F, Taghizadeh M, et al. Selenium Supplementation Affects Insulin Resistance and Serum hs-CRP in Patients with Type 2 Diabetes and Coronary Heart Disease. Horm Metab Res. 2016, 48(4): 263-268.
Hasani M, Djalalinia S, Sharifi F, Varmaghani M. Effect of Selenium Supplementation on Lipid Profile: A Systematic Review and Meta-Analysis. Horm Metab Res. 2018, 50(10): 715-727.
Hasani M, Djalalinia S, Khazdooz M, Asayesh H. Effect of Selenium Supplementation on Antioxidant Markers: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Hormones (Athens). 2019, 18: 451-462.
Mahdavi Gorabi A, Hasani M, Djalalinia S, Zarei M. Effect of Selenium Supplementation on Glycemic Indices: A Meta-Analysis of Randomized Controlled Trials. J Diabetes Metab Disord. 2019, 18: 349-362.
Tabrizi R, Akbari M, Moosazadeh M, et al. The Effects of Selenium Supplementation on Glucose Metabolism and Lipid Profiles Among Patients with Metabolic Diseases: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Horm Metab Res. 2017, 49(11): 826-830.
The information presented in this review article is not intended as medical advice and should not be used as such.
31 July 2020